1 Technical Field
The present invention relates to motors having a stator coil comprised of a plurality of unit coils, each of the unit coils being concentratedly wound around one of a plurality of pole cores in two layers in a height direction of the pole core.
2 Description of Related Art
To achieve both size reduction and output increase of a motor, there is available a method of regularly winding a stator coil of the motor and thereby improving the space factors of the stator coil in inter-pole core spaces (i.e., spaces between circumferentially adjacent pole cores of the stator of the motor). However, in the case of the stator coil being a concentratedly-wound coil, lead portions of the stator coil may become obstacles to the process of regularly winding the stator coil.
To solve the above problem, Japanese Patent Application Publication No. JP2012175741A discloses a concentratedly-wound stator coil. The stator coil includes a plurality of parts each being formed by spirally winding a rectangular wire. The spirally-wound parts are stacked in a plurality of layers. Moreover, those portions of the spirally-wound parts which constitute coil ends of the stator coil are bent into an arc shape. Furthermore, the stator coil also includes a plurality of connecting portions (or layer-changing portions) each connecting one adjacent pair of the spirally-wound parts of the stator coil. The connecting portions are arranged in the inter-pole core spaces and thus not bent into the arc shape.
With the above configuration, it is possible to regularly and concentratedly wind the stator coil. However, at the same time, the space factors of the stator coil in the inter-pole core spaces are lowered due to the arrangement of the connecting portions of the stator coil in the inter-pole core spaces.